Introduction & Impressions

I’ve been fortunate to have my hands on an early version of the Sky-Watcher CQ350 mount since before its release in December 2022.

Functionally the CQ350 is easily described as an EQ7, sitting between the well-known EQ6 and EQ8 family members. But in form it is considerably different from either of those mounts, adopting a centre-balanced approach common to iOptron mounts among others. This places the equipment weight more centrally over the pier or tripod. There are further significant differences under the hood, which has led to the new ‘CQ350’ name rather than suggesting it is simply a hybrid of the existing mounts.

While the 35kg payload of the CQ350 sits squarely in the middle of the EQ6 (20kg) and the EQ8 (50kg), in the flesh it feels somewhat closer to the EQ8. I’ve always been conservative though in the load I place on any mount, running by the old-school ethos of using a bigger mount for stability.

Even loaded up with a long dovetail and camera, the Evostar 150ED is well within the load rating for an EQ6, but the Evostar is a big scope exerting a lot of leverage, and it feels much more comfortably and securely mounted on the CQ350. It is also a lot more tolerant of an exposed (windy) environment, such as my expedition with this mount to capture the partial solar eclipse in December 2021.

Between that and the next expedition, I tested the CQ350 in my dome carrying an Astroworx 12” f4 Newtonian (approx. 20-25kg total) and this feels well within the capacity of the mount (rather I’ve already reached the limit of a 2.3 metre Sirius observatory dome!). Note though that this scope already requires two counterweights at the full extremity of the counterweight shaft. If you want to push the capacity of the mount, you’ll need three counterweights (or a longer shaft), while the mount ships with one weight as standard (check with your supplier).

The counterweight shaft is also different to the screw-in approach of other Sky-Watcher mounts. Now the shaft has two bolts which are required to attach it to the mount, but it also has two positions that it can be installed in. There is a standard position and a ‘forward’ position, which angles the counterweight shaft ‘forward’ or out from the legs of the tripod. This should be helpful to avoid a clash with the tripod at lower latitudes (and indeed it became necessary on the Exmouth eclipse expedition at 20 degrees latitude).

The shape of the CQ350 itself sits more comfortably strapped into a car seat than the very boxy profile of the EQ8 and its wide handles. I am not the world’s strongest astrophotographer by any stretch and the CQ350 is a much more manageable exercise to pack and setup remotely than the EQ8. I still would not want to carry the CQ350 any great distance as I have done with smaller mounts on occasion but setting up beside a vehicle with this mount is very realistic for most people.

The same comment goes doubly so for the original EQ8 tripod which is a monster. The CQ350 comes with a still sturdy but much simpler steel tripod, which will need a decent amount of space and length in your vehicle but is much more sensible for transporting to remote sites. The CQ350 has the same tripod interface as the EQ8, so remote users of that mount might prefer to cross-grade to the new more manageable tripod. This also means that if you have access to a pier with an EQ8 plate the CQ350 will fit straight on.

The other observation of the mount is the new locks on both R.A and declination axes. There is both a locking clutch knob and a clutch lever, using the terminology in the manual, but in fact it is not really a clutch at all. It takes a few goes to get the hang of this combo, but they provide a positive ‘lock’ without needing to decide how much pressure to apply on a clutch.

The design of the mount head means that the top of the mount, where the dovetail bar connects, is at a greater distance from the R.A. axis of the mount than the EQ8-R. On my observatory pier, this provides a useful increase in clearance around the top plate of the pier but does mean that the weight of the scope is slightly further from the rotational axis and requires a corresponding increase in the position of the counterweights (or additional mass).

Connections

The CQ350 offers identical connections on the mount as the EQ8-R. The mount accepts a USB3 cable and provides a hub on the mount head with four USB3 ports. As well as power to the mount itself, there is a separate but single 12V supply socket on the mount base which feeds three DC supply sockets on the mount head (meaning you cannot independently switch them remotely).

There are also three AUX ports on the base and mount head, which can be used to provide relay/switching functions or provide a low power supply of their own. The AUX cables can carry 0.5A per pin, or if keen, you can also twist wires of the AUX cables together as I have done in the dome to get independently switchable power supply from the mount base to the mount head while using the through mount cabling.

Note that on this centre-balanced mount that the worm gear (screw) is on the ‘live’ part of the mount which drives itself around a worm wheel which is fixed to the stationary base of the mount. This is a fundamental rearrangement of the mechanics of the mount compared to the EQ8. All the cables to the mount are connected to this rotating mid-section of the mount, rather than some of the cabling being to a fixed based as on the EQ8.

This seems quite strange at first glance but does make sense. There is very little movement at this point on the mount – just rotation around the R.A. axis which they are close to the centre of. The benefit though is that all the through mount cabling only needs to be routed through the declination axis. It may also be feasible to add your own through mount cabling whereas that appears quite difficult to attempt on the EQ8.

Polar Alignment

There is no option for a polar alignment scope with the CQ350. As noted above, I’m a bit old-fashioned and pretty comfortable aligning mounts with a polar scope. But I am also adaptable and have been getting more used to using PHD drift alignment tools for more accurate polar alignment, without having to crouch down below the mount and peer awkwardly though a polar scope.

As it shares the same tripod interface as the EQ8-R, the bolts for locking down the azimuth of the mount are largely unchanged (perhaps slightly larger washers). There is now a single large knob for adjusting mount altitude (rather than needing to slide a rod through a hole in the adjusting shaft on the EQ8). More importantly, there are new screws to lock the altitude of the mount which do not have the impact on alignment that the previous mechanism did on the EQ8.

As with the EQ8-R, the CQ350 has home position sensors, so you can initiate a homing sequence to accurately set the starting position for the mount or recover it after a power loss.

Control and Performance

For anyone familiar with the Sky-Watcher EQ6 and EQ8/EQ8-R, the CQ350 performs as expected. The same ASCOM drivers work for the new mount, and I had no trouble connecting with Green Swamp Server as the interface between Voyager observatory control and the mount (just check the baud rate if you encounter issues).

The periodic error I measured with PHD2 is around 10-20” (arc-seconds) peak-to-peak over a worm period of 4 minutes. There is no option for high-resolution (but expensive) encoders on the CQ350 as available on the EQ8-Rh.

Slew speeds for the CQ350 are similar to the EQ8-R, but it is noisier. Using PHD2 mount analysis tools, I recorded declination backlash of 5” compared to 20-35” on the EQ8-R. This may be an outcome of the new worm gear design, or simply variation from one sample to the next (or even position on the worm wheel).

Road Test

As well as conducting this review, the plan from the beginning had been to use the CQ350 for an expedition to the Exmouth total solar eclipse in April 2023, by far my most complicated astrophotography expedition yet.

The CQ350 was carrying two large refractors and formed a core part of my gear for that expedition (alongside the EQ8-Rh with an even bigger refractor!). It is a great relief to say that expedition has been completed successfully. The CQ350 was more than capable of handling the bulky combination of an Esprit 100 and EvoStar 150 (note the forward angle of counterweight shaft and mount size compared to EQ8 on the right). The power of being able to carry all these scopes is lots of data.. at the bottom of the page is an integration of images through the EvoStar 150ED, which captured 135 images at 1/8 sec through totality, mounted on the CQ350.

I would note though that the CQ350 is not well suited to side-by-side scopes. The chuck on the head of an EQ6 or EQ8 can be rotated 90 degrees to accommodate side-by-side configuration while still accessing all declinations before hitting the internal hard stops (in the case of the EQ8). The chuck on the CQ350 cannot be rotated in the same way, therefore losing access to a significant range of declinations on one side of the meridian. Either you need to install an extra dovetail adapter at 90-degree in between, or if using two scopes mount them vertically rather than side-by-side. Unlike me taking four scopes to the other side of the country, for most people this is unlikely to be issue.

The only fault I ran into after 5,000km on the road from central Victoria to Exmouth was the grub screws on the R.A. camshaft which worked themselves loose. This meant the camshaft could not act to properly lock the worm against the wheel. Easily remedied and may be improved in future production versions of the mount. The photo below shows the camshaft – hopefully you can see how it acts to push the worm against the main wheel when locking that axis, with springs there to ensure the worm retracts when the lock is released.

Summary

The CQ350 slots into an obvious gap in size between the venerable EQ6 and the hefty EQ8 and is therefore easily described as an EQ7 in all but name.

For observers and especially photographers wanting a remote setup with greater capacity than the EQ6 but something more realistic than the weight and bulk of the EQ8-R, the CQ350 fits the bill nicely.

And for anyone setting up a home observatory, the CQ350 offers enough payload to meet most people’s dreams, while saving a few dollars compared to the EQ8-R to put towards whatever goes on top.

2023 Solar Prominences and Corona, 930mm Field of View (EvoStar 150ED on CQ350 mount)

Full Disclosure: Sky-Watcher Australia loaned this mount for review and to support my 2023 Exmouth eclipse expedition. As a Sky-Watcher Australia ambassador, I hope the blog above is helpful albeit not a completely independent review.